Information.IsDBNull(Object) Method
Definition
Important
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Returns a Boolean value indicating whether an expression evaluates to the DBNull class.
public:
static bool IsDBNull(System::Object ^ Expression);public static bool IsDBNull(object? Expression);public static bool IsDBNull(object Expression);static member IsDBNull : obj -> boolPublic Function IsDBNull (Expression As Object) As BooleanParameters
- Expression
- Object
Required. Object expression.
Returns
Returns a Boolean value indicating whether an expression evaluates to the DBNull class.
Examples
This example uses the IsDBNull function to determine if a variable evaluates to DBNull.
Dim testVar As Object
Dim nullCheck As Boolean
nullCheck = IsDBNull(testVar)
testVar = ""
nullCheck = IsDBNull(testVar)
testVar = System.DBNull.Value
nullCheck = IsDBNull(testVar)
' The first two calls to IsDBNull return False; the third returns True.
Remarks
IsDBNull returns True if the data type of Expression evaluates to the DBNull type; otherwise, IsDBNull returns False.
The System.DBNull value indicates that the Object represents missing or nonexistent data. DBNull is not the same as Nothing, which indicates that a variable has not yet been initialized. DBNull is also not the same as a zero-length string (""), which is sometimes referred to as a null string.
